Waterproof adhesive composition



PatentedApr. 27,1943 a UNITED? prince-1 I WATERPROOF ADHESIVE COMPOSITION- -Brook-J. Dennison, Aspinwall, .Pa., assignor to Pittsburgh Plate Glass company, Allegheny (Minty, Pa, a corporation of Pennsylvania No Drawing. Application June 9, 1939,

Serial No. 278.214 6 (Jaime. ((2. 260-32).

. The present invention relatesto a new waterbut the exposed. edges of the bond were still proof adhesive composition and primarily to a subject to moisture penetration resulting in separesin-silicate mixture suitable as a bonding agent ration of the laminated sheet. I for laminating materials. Briefly stated, the present invention contem- One object of the invention is the provision plates the development of adhesives in which a of an adhesivecomposition which may be used bond unaffected-by moisture is obtained. to unite various materials with the formation of The vinyl acetal resins have recently come into a bond impervious to moistur prominence in the preparation of laminated glass Other objects and advantages of the invention because of their direct adhesion to glass and will become more apparent from the following 10 their resistance to moisture penetration. At the detailed description or certain preferred embodisame time, ho'wever, these vinyl acetal resins are ments thereof. not equally as efiective in bonding wood to glass. It is well recognized that manyforms of ad- It has been found, however, that the addition of hesives have been developed and are in commerrelatively small amounts of partially hydrolyzed cial use. It is equally true that certain of these 1 Organic silicates to a vinyl acetal resin increases adhesives are applicable only to special uses. the adhesiveness thereof and also the moisture For example, a water soluble cement may be used resistan e of th vinyl resin. to unite materials where there is no possibility I m awar h t Organic siilcates h v been of subsequent exposure to moisture. Unforused in combination with cellulosic piastics, but tunately, in spite of warnings laminated articles the resultant mixture can in no 'way be consid- .bonded together with a water soluble cement are ered as comparable to a composition containing very often exposed to moisture-laden air and the partially hydrolyzed organic silicates and vinyl several laminations consequently separate. A e I Seems quite probable 'hydr lysis greater source of possible trouble arises where of the organic silicates yields a condensation two or more laminae of difi'erent materials are product a e n s c d nd coho attempted to be bonded together. As' contemplated by my invention 50 parts of It has been proposed to unite wood veneer and r ni i a 50 Parts of denatured alcohol, glass to obtain special decorative eiiects and a 10 Parts Of Water and a trace f hy r chloric acid suitable adhesive for this purpose must be eiiecre refluxed for approximately one hour to bring I ve not only with the porous wood veneer, but the organic silicate to the proper degree of also with the non-porous glass. Certain prochydrolysis. This treatment is presumedto result esses have been developed which have been utiin the formation of a compound of the typelized in the industry, but it is readily apparent that considerable improvement is still possible A therein. The slight thickness of the wood veneer 1-0-1 and considerable variation in that thickness re- -a R sults in an imperfectly bonded product. An increase in the thickness of adhesive layer or the $33 represents the organic radicle of the application of a reinforcing layer to the article An increase in the ratio of water to ester will before laminating would insure a uniform suro resmtm a compound of the type 1 face adhesion, but the bonded article still fails on exposure to moisture. -R 0-R 0R Tests conducted in the laboratory show that R-o-eLo i-0 rho-R the bond did not separate between the plastic i R i v i and the wood venee which would normally. be

expected, due to the porosity of the wood film, in which a: is a function of the ratio.

but rather that the separation was between the. The partially hydrolyzed organic silicateis ad- 7 plastic and the glass. This result may be exmixed with an equal amount of vinyl acetal plained by the fact. that adhesion of plastic to res n and. the two materials are dissolved in 'an' glass is largely specific, whereas the adhesion of 5 organic solventto provide an adhesive composiplastic to wood is mechanical, and the specific tion, which is in a form most readily used. It adhesion is more readily destroyed when exposed has been ascertained that any of the vin acetal to moisture. Application of varnish, shellac, or resins, such as vinyl formate, vinyl acetate and I paint to the exposed surface of the wood veneer vinyl butyratemay e employed in compounding retarded moisture penetration to some degree, so the adhesive, andiijitis so desired small amounts of plasticizing agents may be incorporated with the resin. The fact that the presence of plasticizing agents does not impair the value of the adhesive compound aiiords an outlet for vinyl scrap accumulating from the production of safety glass.

A more specific example or an adhesive composition as contemplated by my invention is:

In the foregoing example percentages are of course expressed in accordance with conventional nomenclature in terms of the weights or the constituents.

Methyl, propionyl or butyl silicates may be substituted in the composition and other alcohols, or similar organic solvents may be utilized in preparing the adhesive solution.

An adhesive coating of the above-described composition was applied to sections of wood veneer and plates of glass which were united and laminated. at approximately 200 F. under 90 pounds pressure per square inch. These composite plates were subjected to test in a closed chamber heated to 120 F. and containing 100 per cent relative humidity. At the end of 24 hours no separation had occurred. .At the end of '72 hours the composite plates remained unchanged. Under equivalent conditions test plates bonded together with ordinary adhesives were subject to extreme separation.

It was observed that the wood veneer lamina of the composite unit absorbed considerable water and in order to prevent this moisture penetration the wood veneer should be coated with a regular water resistant spar varnish.

The disclosed adhesive composition may be used to form a moisture impervious coating over normally porous materials. In this connection a solution oi vinyl resin and organic silica is brushed over the material to be protected and the solvent is then evaporated. The protective coating will bond very tightly the absorbent material. It has also been found that the coated material may be sprayed with water before it is heated to drive oil the solvent contained in the covering layer and again a very secure bond is eflected.

The disclosed adhesive composition is also susceptible of many otheruses. For example, it

Per cent Vinyl res 10 Partially hydrolyzed ethyl silicate l Methanol '10 Denatured ethanol may be employed to bond class to metal or wood to metal. It may serve as a cement in Joining glass to glass or wood to wood, and in fact as a cement generally.

It will at once be apparent that various modifl cations in the composition of the adhesive solution and the ingredients admixed therewith are possible without departing from the spirit of the invention or the scope of the appended claims.

What I claim is:

1. A waterproof adhesive composition comprising a mixture of vinyl acetal resin and a partially hydrolyzed alkyl ester of siliclc acid obtained by hydrolyzation of an ortho-alkyl silicate inthe ratio of 50 parts of ortho-alkyl silicate and 10 parts of water, the parts being by weight.

2. A water-resistant adhesive composition-comprising a mixture ofvinyl acetal resin "and a partially hydrolyzed ethyl silicate obtained by hydrolyzing approximately parts 01 orthoethyl silicate and 10 parts of water, the parts being by weight.

3. A water-resistant adhesive composition comprising a mixture of vinyl acetal resin'and partially hydrolyzed ethyl silicate dissolvedin an organic solvent, the said hydrolyzation being eflected by the inner action of approximately 50 parts of ethyl silicate and 10 parts oi water,

said parts being by weight.

4. A water-resistant adhesive composition comprising a mixture of vinyl butyral resin and partially hydrolyzed ethyl silicate dissolved in water, the partially hydrolyzed ethyl silicate being obtained by hydrolyzing approximately 50 parts of silicate and 10 parts of water, the parts being by weight.

5. A water-resistant adhesive composition comprising a solution of vinyl butyral resin, a plasticizer for the resin and partially-hydrolyzed ethyl silicate in a mixture of methanol and ethanol, the hydrolyzed ethyl silicate being obtained by hydrolyzing approximately 50 parts of ethyl silicate with 10 parts of water, the parts being by weight.

6. A waterproof adhesive composition comprising approximately 10 percent of plasticized vinyl butyral resin, 10 percent of partially hydrolyzed ethyl silicate, '70 percent of methanol and 10 percent of ethanol, the partially hydrolyzed ethyl silicate being obtained by hydrolyzing approximately 50 parts of ethyl silicate with 10 parts of water, the parts being by weight.

BROOK J. DENNISON. 

